Covers for wagons, railroad cars and various other containers are known. Occasionally a tarp or a similar flexible cover is fastened in place. Additionally, however, covers made from wood, fiberglass or some other more rigid material are used. Known covers either completely close the top of a container or include a moveable door or gate portion which is hinged or has a complex track assembly.
With respect to an agricultural combine, it is known that a cover aids in retaining seed or grain while operating in high winds. Also, a cover can protect from weather elements such as rain, snow and other forms of precipitation. Early combine hopper covers were metal, which were heavy and difficult to use. A more recent fiberglass cover is known, but it is a single element and, consequently, when fastened in placed, it is difficult to remove to inspect grain or otherwise check the hopper contents.
Thus, farmers have extremely expensive combining machinery available to them, but have not been able to adequately protect harvested grain during the harvesting process. When known covers are used, they are used with difficulty and often result in the farmer getting frustrated and disgarding the cover.